Monkeypox virus viral chemokine inhibitor (MPV vCCI), a potent inhibitor of rhesus macrophage inflammatory protein-1

Monkeypox virus (MPV) is an orthopoxvirus with considerable homology to variola major, the etiologic agent of smallpox. Although smallpox was eradicated in 1976, the outbreak of MPV in the U.S. highlights the health hazards associated with zoonotic infections. Like other orthopoxviruses, MPV encodes a secreted chemokine binding protein, vCCI that is abundantly expressed and secreted from MPV infected cells. EMSA data shows vCCI efficiently binds rhesus MIP-1α (rhMIP-1α) at near one to one stoichiometry. In vitro chemotaxis experiments demonstrate that vCCI completely inhibits rhMIP-1α mediated chemotaxis, while in vivo recruitment assays in rhesus macaques using chemokine-saturated implants show a decrease in the number of CD14⁺ cells responding to rhMIP-1α when vCCI is present, suggesting vCCI is effectively inhibiting chemokine function both in vitro and in vivo. More importantly, we demonstrate that vCCI can diminish the severity of the acute phase and completely inhibit the relapsing phase of experimental allergic encephalomyelitis (EAE) disease. These data represent the first in vitro and in vivo characterization of vCCI emphasizing its function as a potent inhibitor of rhMIP-1α. Furthermore, the ability of vCCI to inhibit relapsing EAE disease represents a novel therapeutic approach for treating chemokine-mediated diseases.     

Pleiotropic effects of the Bcg gene. I. Antigen presentation in genetically susceptible and resistant congenic mouse strains

The Ag-presentation ability of Bcgr and Bcgs spleen cells was studied in two sets of Bcg-congenic systems; namely, the BALB/c-BALB/c.Bcgr pair and the B10.A-B10.A-Bcgr pair, by using three sonicated soluble bacterial Ag (mycobacterium bovis bacillus Calmette-Guérin, Salmonella typhimurium, and Brucella abortus) as well as a particulate Ag (heat-killed Escherichia coli). Pulsed Bcgr spleen cells were shown to induce a stronger proliferation of the T cell-indicator system than their Bcgs counterparts. No difference in Ag-presenting ability could be shown between Bcgr and Bcgs peritoneal macrophages from normal animals. However, elicited peritoneal macrophages from immune Bcgr mice were superior in their Ag-presentation ability. Differences at the level of Ag presentation of Bcgr and Bcgs splenic cells were investigated further. Depletion of T cells and B cells did not alter the differences in Ag-presenting ability between Bcgr and Bcgs spleen cells. Furthermore, splenic dendritic cells of Bcgr or Bcgs allelic types were equally efficient in presenting bacillus Calmette-Guérin Ag to accessory cell-depleted T cells. In a final experiment, it was shown that spleen macrophages were the cell type involved in the superior Ag presentation by Bcgr splenic cells.     

Upregulation of MIP-2 (CXCL2) expression by 15-deoxy-Delta(12,14)-prostaglandin J(2) in mouse peritoneal macrophages

A peroxisome proliferator-activated receptor gamma (PPARgamma) ligand, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), has been reported to possess anti-inflammatory activity in activated monocytes/macrophages. In this study, we investigated the effect of 15d-PGJ(2) on the lipopolysaccharide (LPS)-induced expression of chemokine mRNAs, especially macrophage inhibitory protein (MIP)-2 (CXCL2), in mouse peritoneal macrophages. The inhibitory actions of the natural PPARgamma ligands, 15d-PGJ(2) and prostaglandin A1 (PGA1), on the expression of RANTES (regulated upon activation, normal T expressed and secreted; CCL5), MIP-1beta (CCL4), MIP-1alpha (CCL3), IFN-gamma-inducible protein 10 kilodaltons (IP-10; CXCL10) and monocyte chemoattractant protein-1 (MCP-1; CCL2) mRNA in LPS-treated cells were stronger than those of the synthetic PPARgamma ligands troglitazone and ciglitazone. However, 15d-PGJ(2) enhanced the expression of LPS-induced MIP-2 (CXCL2) mRNA. A specific PPARgamma antagonist (GW9662) had no effect on the inhibitory action of 15d-PGJ(2) and PGA1 in LPS-induced chemokine mRNA expression and on the synergistic action of 15d-PGJ(2) in LPS-induced MIP-2 (CXCL2) expression. Moreover, LPS itself reduced the expression of PPARgamma. Although the synergistic effect of 15d-PGJ(2) on LPS-induced MIP-2 (CXCL2) mRNA expression was remarkable, the production of MIP-2 (CXCL2) in cells treated with 15d-PGJ(2) and LPS did not increase compared to the production in cells treated with LPS alone. The synergistic action of 15d-PGJ(2) on LPS-induced MIP-2 (CXCL2) mRNA expression was dependent on the activation of nuclear factor-kappaB (NF-kappaB), and 15d-PGJ(2) increased the phosphorylation of p38 and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) in cells stimulated with LPS. These results suggest that the synergistic effect of 15d-PGJ(2) on LPS-induced MIP-2 (CXCL2) expression is PPARgamma-independent, and is mediated by the p38 and SAPK/JNK pathway in mitogen-activated protein kinase signaling pathways, which activates NF-kappaB. Our data may give more insights into the different mechanisms contrary to the anti-inflammatory effect of 15d-PGJ(2) on the expression of chemokine genes.     

IL-4 is required to prevent filarial nematode development in resistant but not susceptible strains of mice

The murine Litomosoides sigmodontis model of filarial infection provides the opportunity to elucidate the immunological mechanisms that determine whether these nematode parasites can establish a successful infection or are rejected by the mammalian host. BALB/c mice are fully susceptible to L. sigmodontis infection and can develop patent infection, with the microfilarial stage circulating in the bloodstream. In contrast, mice on the C57BL background are largely resistant to the infection and never produce a patent infection. In this study, we used IL-4 deficient mice on the C57BL/6 background to address the role of IL-4 in the development of L. sigmodontis parasites in a resistant host. Two months after infection, adult worm recovery and the percentage of microfilaraemic mice in infected IL-4 deficient mice were comparable with those of the susceptible BALB/c mice while, as expected, healthy adults were not recovered from wild type C57BL/6 mice. The cytokine and antibody responses reveal that despite similar parasitology the two susceptible strains (BALB/c and IL-4 deficient C57BL/6) have markedly different immune responses: wild type BALB/c mice exhibit a strong Th2 immune response and the IL-4 deficient C57BL/6 mice exhibit a Th1 response. We also excluded a role for antibodies in resistance through infection of B-cell deficient C57BL/6 mice. Our data suggest that the mechanisms that determine parasite clearance in a resistant/non-permissive host are Th2 dependent but that in a susceptible/permissive host, the parasite can develop in the face of a Th2 dominated response.     

CD4+ T cell migration into the cornea is reduced in CXCL9 deficient but not CXCL10 deficient mice following herpes simplex virus type 1 infection

The role of CXCL9 and CXCL10 in the ocular immune response to herpes simplex virus type 1 (HSV-1) infection was investigated using mice deficient in either CXCL9 or CXCL10. CXCL10 but not CXCL9 deficient mice showed an increase in sensitivity to ocular virus infection as measured by an elevation in virus titer recovered in the tear film and corneal tissue. The increase in virus was associated with an increase in the expression of the chemokine CCL2 but no significant change in the infiltration of CD4(+) T cells or NK cells into the corneal stroma. In contrast, a significant reduction in CD4(+) T cell infiltration into the cornea was found in CXCL9 deficient mice following HSV-1 infection consistent with the absence of CXCL9 expression and reduction in expression of other chemokines including CCL3, CCL5, CXCL1, and CXCL10. Collectively, the results suggest a non-redundant role for CXCL9 and CXCL10 in response to ocular HSV-1 infection in terms of controlling virus replication and recruitment of CD4(+) T cells into the cornea.     

Oxidant-mediated AA release from astrocytes involves cPLA(2) and iPLA(2)

Excessive generation of reactive oxygen species (ROS) in the central nervous system (CNS) is a leading cause of neuronal injury. Despite yet unknown mechanisms, oxidant compounds such as H₂O₂ have been shown to stimulate the release of arachidonic acid (AA) in a number of cell systems. In this study, H₂O₂ and menadione, a compound known to release H₂O₂ intracellularly, were used to examine the phospholipases A₂ (PLA₂) responsible for AA release from primary murine astrocytes. Both H₂O₂ and menadione dose-dependently stimulated AA release, and the release mediated by H₂O₂ was completely inhibited by catalase. H₂O₂ also stimulated phosphorylation of extracellular signal-regulated kinases (ERK1/2) and cytosolic phospholipase A₂ (cPLA₂). However, complete inhibition of cPLA₂ phosphorylation by U0126, an inhibitor for mitogen-activated protein kinase kinase (MEK) and GF109203x, a nonselective PKC inhibitor preferring the conventional and novel isoforms, only reduced H₂O₂-stimulated AA release by 50%. MAFP, a selective, active, site-directed, irreversible inhibitor of both cPLA₂ and the Ca²⁺-independent iPLA₂, nearly completely inhibited H₂O₂-mediated AA release; but, HELSS, a potent irreversible inhibitor of iPLA₂, only inhibited H₂O₂-mediated AA release by 40%. Along with the observation that H₂O₂-mediated AA release was only partially inhibited upon chelating intracellular Ca²⁺ by BAPTA, these results indicate the involvement of both cPLA₂ and iPLA₂ in H₂O₂-mediated AA release in murine astrocytes.     

Interaction of mouse hepatitis virus 3 with Kupffer cells explanted from susceptible and resistant mouse strains. Antiviral activity, interleukin-1 synthesis

Abstract The genetic sensitivity of mouse strains to mouse hepatitis virus 3 (MHV 3) has been related in vitro to a delay of virus replication in liver sinusoidal cells. In vivo immuno-histochemical studies of the liver from infected mice have demonstrated that mechanisms other than direct viral injury are in operation. To examine potential mechanisms, the interaction of lipopolysaccharide (LPS)-stimulated Kupffer cells with MHV 3 was studied. We first observed a dramatic inhibition in viral replication in LPS-treated Kupffer cells explanted from A/J resistant mice. Second, we demonstrated that MHV 3 induced a dose-dependent interleukin 1 (IL-1) activity in the supernatants of infected Kupffer cells of both strains. These results led us finally to examine the antigen-proceesing function of the Kupffer cellsof both strains of mice. No striking differences were observed in the ability of Kupffer cells from resistant or sensitive mice to collaborate with immunocompetent lymphocytes. Our data suggest that Kupffer cells play a double role which is crucial in the pathogenesis of MHV 3-induced hepatitis. First, they act directly as the genetically determined sensitivity of mice to MHV 3 infection is correlated with the efficiency of the antiviral activity induced in Kupffer cells by LPS. Second, they act indirectly through the synthesis of different amounts of IL-1 induced by MHV 3. This hypothesis is further borne out by the effects of indomethacin treatment on the course of MHV 3 infection in A/J resistant mice in vivo.     

The Th1/Th2 balance does not account for the difference of susceptibility of mouse strains to Theiler's virus persistent infection.

Theiler's virus causes a persistent infection with demyelination that is studied as a model for multiple sclerosis. Inbred strains of mice differ in their susceptibility to viral persistence due to both H-2 and non-H-2 genes. A locus with a major effect on persistence has been mapped on chromosome 10, close to the Ifng locus, using a cross between susceptible SJL/J and resistant B10.S mice. We now confirm the existence of this locus using two lines of congenic mice bearing the B10.S Ifng locus on an SJL/J background, and we describe a deletion in the promoter of the Ifng gene of the SJL/J mouse. We studied the expression of IFN-gamma, IL-2, IL-10, and IL-12 in the brains of SJL/J mice, B10.S mice, and the two lines of congenic mice during the first 2 wk following inoculation. We found a greater expression of IFN-gamma and IL-2 mRNA in the brains of B10.S mice compared with those of SJL/J mice. Also, the ratio of IL-12 to IL-10 mRNA levels was higher in B10.S mice. However, the cytokine profiles were the same for the two lines of resistant congenic mice and for susceptible SJL/J mice. Therefore, the difference of Th1/Th2 balance between the B10.S and SJL/J mice is not due to the Ifng locus and does not account for the difference of susceptibility of these mice to persistent infection.     

Transmission of mouse minute virus (MMV) but not mouse hepatitis virus (MHV) following embryo transfer with experimentally exposed in vivo-derived embryos

The present study investigated the presence and location of fluorescent microspheres having the size of mouse hepatitis virus (MHV) and of mouse minute virus (MMV) in the zona pellucida (ZP) of in vivo-produced murine embryos, the transmission of these viruses by embryos during embryo transfer, and the time of seroconversion of recipients and pups. To this end, fertilized oocytes and morulae were exposed to different concentrations of MMVp for 16 h, while 2-cell embryos and blastocysts were coincubated for 1 h. In addition, morulae were exposed to MHV-A59 for 16 h. One group of embryos was washed, and the remaining embryos remained unwashed before embryo transfer. Serological analyses were performed by means of ELISA to detect antibodies to MHV or MMV in recipients and in progeny on Days 14, 21, 28, 42, and 63 and on Days 42, 63, 84, 112, 133, and 154, respectively, after embryo transfer. Coincubation with a minimum of 10(5)/ml of fluorescent microspheres showed that particles with a diameter of 20 nm but not 100 nm crossed the ZP of murine blastocysts. Washing generally led to a 10-fold to 100-fold reduction of MMVp. Washed MMV-exposed but not MHV-exposed embryos led to the production of antibodies independent of embryonic stage and time of virus exposure. Recipients receiving embryos exposed to a minimum of 10(7) mean tissue culture infective dose (TCID(50))/ml of MHV-A59 and 10(2) TCID(50)/ml of MMVp seroconverted by Day 42 after embryo transfer. The results indicate that MMV but not MHV can be transmitted to recipients even after washing embryos 10 times before embryo transfer.     

Relationship between complement membrane attack complex, chemokine (C-C motif) ligand 2 (CCL2) and vascular endothelial growth factor in mouse model of laser-induced choroidal neovascularization

The present study investigated the interactions among the complement membrane attack complex (MAC), CCL2, and VEGF that occur in vivo during the development of choroidal neovascularization (CNV). We first investigated the sequential expression of MAC, CCL2, and VEGF during laser-induced CNV in C57BL/6 mice. Increased MAC deposition was detected at 1 h, CCL2 increased at 3 h, and VEGF was up-regulated at day 3 post-laser treatment. These results suggested that during laser-induced CNV, MAC, CCL2 and VEGF are formed and/or expressed in the following order: MAC → CCL2 → VEGF. To determine the cross-talk between MAC, CCL2, and VEGF during laser-induced CNV, neutralizing antibodies were injected both systemically and locally to block the bioactivity of each molecule. Blocking MAC formation inhibited CCL2 and VEGF expression and also limited CNV formation, whereas neutralization of CCL2 bioactivity did not affect MAC deposition; however, it reduced VEGF expression and CNV formation. When bioactivity of VEGF was blocked, CNV formation was significantly inhibited, but MAC deposition was not affected. Together, our results demonstrate that MAC is an upstream mediator and effect of MAC on the development of laser-induced CNV can be attributed to its direct effect on VEGF as well as its effect on VEGF that is mediated by CCL2. Understanding the interplay between immune mediators is critical to gain insight into the pathogenesis of CNV.     

家蚕对浓核病毒中国株(BmDNV-3)抗性及感性品系中肠的差异蛋白质分析

【目的】通过比较家蚕Bombyx mori抗性及感性品系的中肠蛋白质表达谱,获得家蚕对家蚕浓核病毒中国株（BmDNV-3）抗性相关的蛋白。【方法】利用双向电泳(2-DE)对感性品种华八35和抗性品种秋丰接种病毒后48 h的蛋白质表达谱进行比较分析,并对其中的差异蛋白进行MALDI-TOF-TOF质谱分析,通过NCBInr和MSDB数据库进行蛋白点的鉴定和功能分析。【结果】获得重复性较好的差异蛋白点16个,其中质谱鉴定出5种蛋白,它们分别是糖基转移酶（glycosyltransferase）、糖基转移酶-S（GlcAT-S）、21.5 kD小热休克蛋白（21.5 kD small heat shock protein）、V-ATP酶（vacuolar ATP synthase）和精氨酸激酶（arginine kinase）。这5种蛋白在抗性品系秋丰中的表达量均高于感性品系华八35。【结论】糖基转移酶和糖基转移酶-S仅在抗性品系中存在,提示它们可能是与抗性有关的蛋白。此外,增强的应激反应和能量代谢也可能与家蚕对BmDNV-3的抗性产生相关。     

Aphid infestation induces PR-proteins differently in barley susceptible or resistant to the birdcherry-oat aphid (Rhopalosiphum padi)

The effect of infestation by the birdcherry-oat aphid ( Rhopalosiphum padi L.), on induction of PR-proteins was investigated in barley ( Hordeum vulgare L.), using barley lines susceptible or resistant to R. padi. The PR-proteins PR-1a (unknown function), PR-5a (acidic thaumatin) and peroxidase (EC 1.11.1.7) were not affected, whereas one chitinase (EC 3.2.1.14) and 4 β -1,3-glucanases (EC 3.2.1.39) were induced by the aphid treatment. In the resistant breeding line CI 16145, but not in the susceptible cultivar Golf, accumulation of one basic chitinase and two acidic β -1,3-glucanases increased with time from 2 until 11 days after infestation, as determined by western blots, with antibodies raised against purified chitinase (PR-3a) and β -1,3-glucanase (PR-2a) from barley. By isoelectric focusing, two additional basic β -1,3-glucanases were detected, which increased after infestation in both the resistant and the susceptible barley. The basic chitinase was only detected at days 7 and 11 in the susceptible cultivar, but already at day 2 in the resistant line. The induction was localized to the infested leaf. The PR-proteins PR-3a and PR-2a were also induced by the fungal pathogen ( Blumeria [syn. Erysiphe ] graminis f. sp. hordei ), methyl salicylate and, to a lower extent, by wounding with tweezers and methyl jasmonate (MeJA). Needle wounding performed to mimic aphid stylet penetration did not induce chitinase or β -1,3-glucanase. It is concluded that the fungal pathogen and the aphid infestation induce both similar and different responses, and that the aphid induction is not due to wounding only. The different responses in resistant and susceptible lines indicate that the induced enzymes may play a role in the resistance against aphid infestation.     

Deficiency in indoleamine-2, 3-dioxygenase induces upregulation of guanylate binding protein 1 and inducible nitric oxide synthase expression in the brain during cerebral infection with Toxoplasma gondii in genetically resistant BALB/c mice but not in genetically susceptible C57BL/6 mice

We examined the roles of indoleamine-2, 3-dioxygenase 1 (IDO1) in controlling cerebral Toxoplasma gondii infection in both genetically resistant and susceptible strains of mice. In susceptible C57BL/6 mice, IDO expression was immunohistochemically detected only in a minority (22.5%) of tachyzoite-infected cells in their brains during the later stage of infection. When C57BL-6-background IDO1-deficient (IDO1^?/?) mice were infected, their cerebral tachyzoite burden was equivalent to those of wild-type (WT) animals. In contrast, in resistant BALB/c mice, IDO expression was detected in a majority (84.0%) of tachyzoite-infected cerebral cells. However, tachyzoite burden in BALB/c-background IDO1^?/? mice remained as low as that of WT mice, which was 78 times less than those of C57BL/6 mice. Of interest, IDO1^?/? mice of only resistant BALB/c-background had markedly greater cerebral expressions of two other IFN-γ-mediated effector molecules, guanylate binding protein 1 (Gbp1) and nitric oxide synthase 2 (NOS2), than their WT mice. Therefore, it would be possible that IDO1 deficiency was effectively compensated by the upregulated expression of Gbp1 and NOS2 to control cerebral tachyzoite growth in genetically resistant BALB/c mice, whereas IDO1 did not significantly contribute to controlling cerebral tachyzoite growth in genetically susceptible C57BL/6 mice because of its suppressed expression in infected cells.     

Among CXCR3 chemokines, IFN-gamma-inducible protein of 10 kDa (CXC chemokine ligand (CXCL) 10) but not monokine induced by IFN-gamma (CXCL9) imprints a pattern for the subsequent development of autoimmune disease

Infection of the pancreas with lymphocytic choriomeningitis virus results in rapid and differential expression among CXCR3 chemokines. IFN-gamma-inducible protein of 10 kDa (IP-10), in contrast with monokine induced by IFN-gamma and IFN-inducible T cell-alpha chemoattractant, is strongly expressed within 24 h postinfection. Blocking of IP-10, but not monokine induced by IFN-gamma, aborts severity of Ag-specific injury of pancreatic beta cells and abrogates type 1 diabetes. Mechanistically, IP-10 blockade impedes the expansion of peripheral Ag-specific T cells and hinders their migration into the pancreas. IP-10 expression was restricted to viruses infecting the pancreas and that are capable of causing diabetes. Hence, virus-induced organ-specific autoimmune diseases may be dependent on virus tropism and its ability to alter the local milieu by selectively inducing chemokines that prepare the infected tissue for the subsequent destruction by the adaptive immune response.     

Morphine induces aggression but not analgesia in the naked mole-rat (Heterocephalus glaber)

1. The antinociceptive effect in the mole-rat of morphine (1, 10, 20 or 30 mg/kg) and nefopam (10 or 20 mg/kg) was studied. 2. In the hotplate test, morphine had no analgesic effect. A reduced response latency after morphine (10 and 20 mg/kg) could possibly be explained by hyperactivity and excited behaviour. 3. After morphine (10, 20 and 30 mg/kg) most of the animals died after fighting when kept in colony cages. Aggressive behaviour and death was prevented by naloxone, or by keeping the animals in single cages. 4. Nefopam (20 mg/kg) significantly increased the latency for the nociceptive response. 5. It was concluded that in the mole-rat, opioid systems in the CNS may not be involved in the regulation of nociception, but in the regulation of agonistic and motor behaviour.     

CXC chemokine receptor 2 but not C-C chemokine receptor 1 expression is essential for neutrophil recruitment to the cornea in helminth-mediated keratitis (river blindness)

Infiltration of neutrophils and eosinophils into the mammalian cornea can result in loss of corneal clarity and severe visual impairment. To identify mediators of granulocyte recruitment to the corneal stroma, we determined the relative contribution of chemokine receptors CXC chemokine receptor (CXCR)-2 (IL-8R homologue) and CCR1 using a murine model of ocular onchocerciasis (river blindness) in which neutrophils and eosinophils migrate from peripheral vessels to the central cornea. CXCR2(-/-) and CCR1(-/-) mice were immunized s.c. and injected into the corneal stroma with Ags from the parasitic helminth Onchocerca volvulus. We found that production of macrophage-inflammatory protein (MIP)-2, KC, and MIP-1 alpha was localized to the corneal stroma, rather than to the epithelium, which was consistent with the location of neutrophils in the cornea. CCR1 deficiency did not inhibit neutrophil or eosinophil infiltration to the cornea or development of corneal opacification. In marked contrast, neutrophil recruitment to the corneas of CXCR2(-/-) mice was significantly impaired (p < 0.0001 compared with control, BALB/c mice) with only occasional neutrophils detected in the central cornea. Furthermore, CXCR2(-/-) mice developed only mild corneal opacification compared with BALB/c mice. These differences were not due to impaired KC and MIP-2 production in the corneal stroma of CXCR2(-/-) mice, which was similar to BALB/c mice. Furthermore, although MIP-1 alpha production was lower in CXCR2(-/-) mice than BALB/c mice, eosinophil recruitment to the cornea was not impaired. These observations demonstrate the critical role for CXCR2 expression in neutrophil infiltration to the cornea and may indicate a target for immune intervention in neutrophil-mediated corneal inflammation.     

Enhanced proliferation of astrocytes from beta(2)-adrenergic receptor knockout mice is influenced by the IGF system

In the present study, we investigated the IGF system in neonatal astrocytes derived from mice with a targeted disruption of the beta-2 adrenergic receptor (β₂AR). β₂AR knockout astrocytes demonstrated higher proliferation rates and increased expression of the astrogliotic marker GFAP, as compared with wild-type cells. β₂AR deletion also regulated molecules of the IGF system. Although IGF-1 levels remained unaltered, IGF-2 and type 1 IGF receptor expression was increased in β₂AR knockout cells. Furthermore, conditioned medium from knockout astrocytes contained lower levels of IGF binding protein-2 and -4. Our data suggest a deficit of β₂AR on astrocytes, as previously reported in multiple sclerosis, may have implications on proliferative status of astrocytes, a feature that might be attributed to regulation of IGF mitogenic actions.     

Lipocalin-2 Is a chemokine inducer in the central nervous system: role of chemokine ligand 10 (CXCL10) in lipocalin-2-induced cell migration

The secreted protein lipocalin-2 (LCN2) has been implicated in diverse cellular processes, including cell morphology and migration. Little is known, however, about the role of LCN2 in the CNS. Here, we show that LCN2 promotes cell migration through up-regulation of chemokines in brain. Studies using cultured glial cells, microvascular endothelial cells, and neuronal cells suggest that LCN2 may act as a chemokine inducer on the multiple cell types in the CNS. In particular, up-regulation of CXCL10 by JAK2/STAT3 and IKK/NF-κB pathways in astrocytes played a pivotal role in LCN2-induced cell migration. The cell migration-promoting activity of LCN2 in the CNS was verified in vivo using mouse models. The expression of LCN2 was notably increased in brain following LPS injection or focal injury. Mice lacking LCN2 showed the impaired migration of astrocytes to injury sites with a reduced CXCL10 expression in the neuroinflammation or injury models. Thus, the LCN2 proteins, secreted under inflammatory conditions, may amplify neuroinflammation by inducing CNS cells to secrete chemokines such as CXCL10, which recruit additional inflammatory cells.